I've checked but there is no references that mentioned of Build 297 of NT 3.1 released in 1992 come with any TCP/IP stack.
It seems TCP/IP stack was still under development at that time and was not included in this early beta build, and it was only released in 1993 stable release. Perhaps the more correct word is not 'development' but 'testing' since they ripped the TCP/IP stack out from Spider system and there's a very high probability that the Spider stack itself was part of BSD codes.
They licensed Spider Software's TCP/IP stack. And you have no knowledge that Spider leveraged BSD code. You're probably too young to remember, but there were many vendors making TCP/IP stacks back in those days. Some based on pre-existing stacks, others from the ground up.
I'm unsure as to why you're making unsubstantiated claims and sticking with them. You have zero proof that the claims you're making are true. I'd love to have the source for Spider's TCP or at least have a contact that worked on the stack to ask, it's interesting history. I don't care one way or another, it was a very temporary stack that didn't make it into 3.5 where the entire stack architecture changed (no longer based on SysV STREAMS).
> Linux wasn't a thing by the time NT was in development
So your statement provided here is wrong and misleading then?
According to this book NT development took five years to complete and reached stable 1.0 version by 1993 [1].
When Linux was in version 0.99 it has had a working implementation of TCP/IP by 1992 then in the very same year Linus relicensed Linux to GPL, and all these happened during NT development, wasn't it?
[1] Showstopper: The Breakneck Race to Create Windows NT and Next Generation at Microsoft:
NT OS/2 started development in 1988 and NT Win32 in 1990.
Build 297 of NT 3.1 contains a TCP/IP stack dated June 25th, 1992. This is not the earliest public build.